Robert Lighthizer, a longtime advocate for steel interests, is the new U.S. trade representative. He says that he wants to free America from “free-trade dogma.” But in practice, that wouldn’t open the door to a smarter economic policy. It would open the door to interest-group payoffs. The steel protectionism Lighthizer has advocated is a case in point, I argue today at Bloomberg View: It hurts the economy but has a powerful political lobby behind it.